Aetiology and pathophysiology of asthma Flashcards
What is asthma?
The hypersensitivity of hyperinflation of airways that become narrow and clogged with mucus in response to certain tirggers
What are the common triggers of asthma?
infection, nighttime or early morning, exercise, animals, cold/damp, dust, strong emotions, occupation exposure, pollutants
What happens to the airway muscle in asthma?
The smooth muscle contracts to make the airways tighter and narrower, the airways become “twitch” and contracts more easily and stronger
What happens to the airways as a result of inflammation?
The inside walls of the airways become swollen and inflames, leaving less space inside them
What happens to mucus in asthma?
It is excessive and can block the inside of the airways
What happens to the lung tissue in patients with asthma?
ongoing inflammation can lead to the development of scar tissue and tissue remodelling. This results in thicked airway walls and increased smooth muscle
What is atopy?
Atopy is a problem with the immune system which makes individuals more likely to develop allergic diseases and sensitive to triggers
When does atopic asthma begin?
It usually begins in childhood, when it is triggered by environmental antigens, such as dusts, pollen, animal dander and foods.
What happens in atopy?
When an allergy enters the body the immune system overacts and created antibodies called immunoglobulin which release chemicals that cause allergy symptoms in your body.
What causes atopy?
Genetic causes, 80% of people with atopy have other family members with allergic diseases.
What are the conditions related to atopy?
Asthma, eczema, allergic rhinitis, allergies to shellfish
What is bronchial hyperresponsiveness?
An increase in sensitivity to a wide variety of airway-narrowing stimuli, which can be both chemical and physical
What does the hyperactivity of the bronchial smooth muscle?
bronchoconstriction, increasing airflow resistance and decreased airflow
What is fixed bronchial hyperresponsiveness more influenced by?
airway inflammation but more by structural changes of the airway which persist after the inflammation has been supressed.
What is episodic bronchial hyperresponsiveness influenced by?
the acute effects of airway inflammation
What type of hypersensitivity response is initiated in asthma?
Typ1 1
What happens in the type 1 hypersensitivity response?
Th2 cells activate downstream B cells to produce immunoglobulin E (Ig-E), which mediates the release of antibodies against the soluble antigen
What is the result of the Ig-E release?
Mast cell degranulation and release of histamine and other inflammatory mediators, including proteinoids, platelet activating factors and leukotrienes, create a cycle of chronic inflammation.
What does chronic inflammation because of type 1 hyperresponsiveness lead to?
bronchoconstriction and epithelial damage, leading to remodelling of the airway and bronchospasm.
What is bronchospasm?
Bronchospasm is when the muscles that line the bronchi start to contract and spasm, which causes airway narrowing
What is the effect of bronchospasm on gas exchange?
This reduces the amount of oxygen that enters the blood and the amount of carbon dioxide that leaves the blood.
What noise is made as a result of bronchospasm and why?
Wheezing, because of bronchoconstriction the airflow through a narrowed airway becomes turbulent, causing vibration of the airway walls; this vibration produces the sound of wheezing.
